Simultaneous removal of Cd (II), Ni (II), and Pb (II) from water by a submerged macrophyte pondweed (Potamogeton malaianus)

Abstract

The current work investigated the potential of submerged macrophyte pondweed (Potamogeton malaianus) in treating cadmium, nickel, and lead-contaminated water through phytoremediation. The adsorption for the three metal ions occurred rapidly within 2 h and attained dynamic equilibrium in no more than 72 h. The removal efficiencies of Cd (II), Ni (II), and Pb (II) were high, passing 94% in both single- and multi-metal systems. The kinetic adsorption curves of Cd (II), Ni (II), and Pb (II) were fitted well by both pseudo-first-order and pseudo-second-order kinetics (R² = 0.9875-0.9995). The equilibrium adsorption capacities of Cd (II), Ni (II), and Pb (II) for P. malaianus were 6.29-6.97 mg kg^-1 . In plants, the higher concentration of each metal ions was accumulated in leaves (12.44-38.15 mg kg^-1 ) than in roots (10.32-26.10 mg kg^-1 ). The chlorophyll contents increased from 0.69 to 0.89-1.00 mg g^-1 under the treatment of Cd (II), Ni (II), and Pb (II), whereas the chlorophyll a/b ratio was kept constant. There was no significant difference between single- and multi-metal systems. FT-IR spectra showed that COH and C═N might be involved in the adsorption of Cd (II), Ni (II), and Pb (II). This study demonstrated that P. malaianus could be a suitable submerged macrophyte for the simultaneous removal of Cd (II), Ni (II), and Pb (II) from water.

Keywords: adsorption; bioaccumulation; multi-metal system; phytoremediation; potentially toxic metal(s).